The present invention relates to an image and sound processing apparatus, and more particularly to a game computer system processing a variety of image and sound data.
Recently, a game computer system manages plural types of data, that is, external block and dot sequence types, and an internal dot sequence type. Further, plural BG (background) pictures are processed to be superimposed in the computer system. In a conventional game computer, these data are processed in a HSYNC or VSYNC period. Therefore, according to the conventional system, it is difficult to process the BG data for each block at a high speed, because a variety types of data must be processed in the HSYNC or VSYNC period.
For example, when image data for a natural picture is processed, a RAM is accessed for each block of the image in an interrupt period, and an area of the RAM corresponding to dots needed to be processed is accessed in the block accessing period. In this case, it is sufficient to access only the dots needed to be processed without the block access, so that the access time is decreased. If dot accessing is realized by forming a special circuit in the system, the circuit becomes very large.
In the conventional computer system, the current address of a RAM is renewed by the CPU using a predetermined program or an increment operation. The increment process is not suitable for a multi-media computer such as a game computer treating a variety of data such as graphic, video, general, sound, etc. According to the conventional game computer, the same data arrangement of the RAM is used for any data mode; however, it is not effective use of the RAM.
In the conventional computer system, the background image is managed by using a BAT (background attribute table) and a CG (character generator) in a VRAM. According to the conventional computer system, the size and position of the BAT in the RAM are fixed, and therefore, a useless area is formed in the RAM, because the size of the image data varies depending on the type and kind of the data.
In game computer systems, it is necessary that the position where the data are currently read in the memory be monitored by a user program, when the data are continuously processed. That is easy to realize if the data are read directly; however, it is impossible to directly monitor the current position when the RAM is accessed automatically at a predetermined interval. In the conventional game computer, the current position must be calculated based on the elapsed time, and as a result, the CPU must perform much processing.